microsoft / microsoft/TypeScript

@ts-expect-error not ignoring next line correctly in JSX, and errors are reported on the same line

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Bug Domain: JSX/TSX Help Wanted
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Description

🔎 Search Terms

"tsx expect error", "jsx expect error"

🕗 Version & Regression Information

It seems as though @ts-expect-error reports errors on the wrong line, when used inside JSX. For example:

function TestNotIgnoring() {
    return <Component>
    <div />
    {/* @ts-expect-error */} <-- error
    {child}
    </Component>
}

function TestIgnoring() {
    return <Component>
    {/* @ts-expect-error */}
    {child}
    </Component>
}

The error in this case is:

Type 'ReactNode | Element' is not assignable to type 'ReactNode'.
  Type 'Element' is not assignable to type 'ReactNode'.
    Type 'Element' is missing the following properties from type 'ReactPortal': type, props, key(2322)
Unused '@ts-expect-error' directive.(2578)

I would have expected no error though, given that that's the behavior when other children are added. Other examples that work are:

function TestIgnoringOnLineAbove() {
    return <Component>
    {/* @ts-expect-error */} <-- moved expect *above* the div, works correctly
    <div />
    {child}
    </Component>
}

I'd expect this to not work though, given that the error is actually on the line with {child} in it

⏯ Playground Link

https://www.typescriptlang.org/play?#code/JYWwDg9gTgLgBAJQKYEMDG8BmUIjgcilQ3wG4BYAKCswFcA7DYCeuAYV0nqXpgAoA3lTgi4aABbAANgBMi9KgF8AXHAFxhoidLk9VydDAB0BjADkIMpEoCUazSKIxaUVgB4ZwAG4A+Adtl5RTcAek9fJSoqNBYAZ3gAmTgAXgIAUQAPFHApJHw4FFi4PlNjUosrOAAfODTckB4YGyjKOkYYZlYAFSR4ixgASQBzemhgeiG+OyFKUTgnF3cOcBZGnwc4D284EPXZ0QEQgCo4AAEYWIBaJAywJAxrqBwoOCOQxQ3-SVkP-ZFQ5ZcNaRaitBhMFhwHrxYajKDjSbTDYLVybQGrXh7OaHE7nK43O4PJBPaCvd6fRK-OYAzgYmB7X40cEdSHQwYjMYTADy9AAMuMkABBABGEC8SCm9j+8yQzlRbnR3Exn2OZwu11u9xgj2eZKpoi2Xh2WIOlI2NJWSvpSiAA

💻 Code
import React from 'react';

function Component({
    children
}: { 
    children: React.ReactNode
}) {
    return <div>{children}</div>
}

const child = 'Example' as (React.ReactNode | Element)

function TestNotIgnoring() {
    return <Component>
    {/* @ts-expect-error */}
    <div />
    {child}
    </Component>
}

function TestIgnoring() {
    return <Component>
    {/* @ts-expect-error */}
    {child}
    </Component>
}

function TestIgnoringOnLineAbove() {
    return <Component>
    {/* @ts-expect-error */}
    <div />
    {child}
    </Component>
}
🙁 Actual behavior

@ts-expect-error was reported unused, and an error was reported on the line including ts-expect error

🙂 Expected behavior

@ts-expect-error should suppress the error, regardless of whatever other elements are added as children prior to the element.

Additional information about the issue

No response

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the linked TypeScript Playground reproduction and compare the two JSX cases where @ts-expect-error is placed before a child expression. Trace how JSX child diagnostics and directive locations are associated, then verify that the directive suppresses the intended error without producing an unused-directive diagnostic.

Written by the indexing model from the issue text.

Assessment

Tech stack
react, typescript
Domain
compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
42/100

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